The present invention relates to an applicator for applying a fluid to a surface. In embodiments, the applicator is useful for applying a medicament-containing fluid to the skin. In particular embodiments, the applicator is useful for applying a topical or transdermal testosterone composition to the skin of a patient in need of testosterone replacement therapy.
It is known from U.S. Pat. No. 8,177,449 to Bayly et al. to provide an implement for applying a volume of liquid containing testosterone to an underarm or axilla skin surface. This implement includes a cylindrical rigid support or handle on which a resiliently deformable thin flexible membrane is mounted. The membrane has a generally circular shape, with an inner circular area or base in contact with, but not secured to, the upper surface of the cylindrical rigid support. The membrane extends upwardly away from the circumference of the fixed inner circular area and is folded over to create an upper folded edge. The membrane then extends back down towards the rigid support, with the outer circumference of the membrane forming a lower outer edge which is fixed in position to the rigid support. With this structure, the secured inner circular area or base, and the upstanding wall, form a reservoir. In operation, a volume of liquid is pumped into the reservoir. The upper folded edge the membrane is then rubbed over the skin surface to which the liquid is to be applied, whereby the upper folded edge spreads the liquid over this skin surface.
However, it has been found that, with the implementation of this patent, the upper folded edge of the membrane tends to deform rather than roll over the skin surface. As a result of this deformation, a seal is difficult to maintain, with some leakage of the liquid from between the implement and the skin surface. In addition, because of this action, underarm hairs tend to be pulled, causing discomfort to the person.